No, they will not honor that. It must have the national rail logo on it. and Both people must have travelcard issued by National Rail.

Paddington station has a National Rail counter (First Great Western) and they have the daysoutguide brochures if you didn't print out your coupons in advance (though only 3 to fill out in each brochure)
I know there are others that do, but if you come from Heathrow to Paddington that makes it easy.